1. Field of the Invention
The present invention relates to an oil supplying and discharging structure for a canceller in a hydraulic clutch including a clutch drum, a clutch piston and a canceller plate which are supported around an outer periphery of a rotary shaft to define a clutch oil chamber between the clutch drum and the clutch piston and a canceller oil chamber between the clutch piston and canceller plate.
Incidentally, the term "oil" used throughout this specification should be understood to cover also any appropriate fluid other than oil, that may be usable for the invention.
2. Description of the Prior Art
Such oil supplying and discharging structures for cancellers in hydraulic clutches are known from Japanese Patent Applications Laid-open Nos. 296072/90 and 296073/90.
There is a problem that if an oil in the canceller oil chamber is not quickly discharged after stopping of an engine, the oil remaining in the canceller oil chamber obstructs and affects the quick engagement of the hydraulic clutch especially at a low temperature at which the viscosity of the oil increases. There is also a problem that if the oil is not quickly supplied to the canceller oil chamber after starting of the engine, a centrifugal hydraulic pressure applied to the oil remaining in the clutch oil chamber cannot be satisfactorily canceled, thereby developing a drag phenomenon on the hydraulic clutch.
In this manner, it is desirable that the oil is quickly discharged from the canceller oil chamber after stopping of the engine and also quickly supplied to the canceller oil chamber after starting of the engine. However, the known structure suffers from a problem that it is difficult to quickly supply and discharge the oil, because of complicated oil supplying and discharging paths connected to the canceller oil chamber.